Add chimera mirror post

v2/content/posts/2024/australian-chimera-linux-mirror.md

@@ -0,0 +1,73 @@
++++
+title = "Australian Chimera Linux Mirror"
+date = 2024-08-25T09:17:27+10:00
+
+#[extra]
+#updated = 2024-06-06T08:24:45+10:00
++++
+
+I have set up a mirror of
+[repo.chimeralinux.org](https://repo.chimera-linux.org/) on a server in
+Australia (Brisbane). It's been running well for a couple of weeks now. The
+[root of the mirror][mirror] shows an index of what is hosted and when it was
+last synced. [/chimera] is where the Chimera data lives.
+
+It mirrors the packages as well as ISO and rootfs downloads. Using the mirror
+greatly speeds up package downloads, which in-turn makes things like `apk
+upgrade` a lot faster. Some rudimentary testing suggests this this server may
+also provide a speed improvement for folks in parts of Asia too.
+
+<!-- more -->
+
+### How to Use the Mirror
+
+#### Packages
+
+Edit the files in `/etc/apk/repositories.d/` to point to the mirror. For example
+`/etc/apk/repositories.d/00-repo-main.list` contains this by default:
+
+```
+https://repo.chimera-linux.org/current/main
+```
+
+Change that to:
+
+```
+https://au.mirror.7bit.org/chimera/current/main
+```
+
+I.e. replace `repo.chimera-linux.org` with `au.mirror.7bit.org/chimera`.
+
+#### Downloads
+
+For ISOs and rootfs images visit: <https://au.mirror.7bit.org/chimera/live/latest/>.
+
+### Building and Running the Mirror
+
+I set up a new server with [BinaryLane] in Brisbane and installed Chimera Linux
+on it—yes the mirror is hosted with Chimera. Specifically I installed the
+[base-minimal] package set to keep the package count low. On top of that I
+installed `nginx` to serve the data and [Lego] (which I added to cports) to
+manage TLS certificates from Let's Encrypt.
+
+To limit access and avoid the use of `root` there are dedicated regular users
+for syncing, `lego`, `nginx`, and `www-data`. To allow `lego` to restart
+`nginx` when certificates are updated I use a [doas] rule.
+
+Synchronisation is triggered hourly by a cron job. I use the [atomic-rsync]
+script to make updates atomic. The script manages a pair of directories
+`chimera-1` and `chimera-2`. The active one is symlinked to `chimera`. The
+script syncs into the inactive directory, creating hard links for unchanged
+data, then flips the symlink at the end.
+
+After syncing, the current date is written to a file, which is used by a small
+snippet of JavaScript on [the index page][mirror] to show when the data was
+last synced.
+
+[mirror]: https://au.mirror.7bit.org/
+[/chimera]: https://au.mirror.7bit.org/chimera/
+[BinaryLane]: https://www.binarylane.com.au/
+[base-minimal]: https://pkgs.chimera-linux.org/package/current/main/x86_64/base-minimal
+[atomic-rsync]: https://github.com/RsyncProject/rsync/blob/9615a2492bbf96bc145e738ebff55bbb91e0bbee/support/atomic-rsync
+[Lego]: https://go-acme.github.io/lego/
+[doas]: https://github.com/Duncaen/OpenDoas